Paint mixing apparatus



June 1940' c. E. FARRINGTON 2,203,135

PAINT MIXING APPARATUS Filed Sept. 15, 1937 2 Sheets-Sheet 1 lrwenlor E FHRR\UGTON 2 Sheets-Sheet 2 Well/Z07 cumwas E rmmnemu n. l I I 1 i 11%| 1 l l wlww A MHU/ June 1940- c. E. FARRINGTON PAINT MIXING APPARATUS Filed Sept. 15, 1937 Patented June 4, 1940 I v UNITED STATES PATENT orrlca ram'r miflzz iirm'rus I Charles E. Farrington, Phoenixville, Pa. 3 9 33133? 121 533111? This invention relates to a mixing apparatus dispersive effect of the stirrer devices, the whole and more particularly toan improved construccombining to provide a dispersion efilciency of a tion of a motor-driven mixer especially suitable degree not heretofore obtainable. for mixing paints and similar liquid or semi-liquid Other objects of the invention and advantages compounds. and economies eifected by the apparatus con- Among the principal objects of the present instructed in accordance therewith will be apparent vention is the provision of a mixing apparatus more fully hereinafter. having a power-driven agitator of such operating The invention consists substantially in the comcharacteristics as to insure a rapid and uniform bination, construction, location and relative ar- 10 dispersion or dissolution of solids iii a liquid body rangement of parts, all as will be described in 10 whereby to produce a liquid or semi-liquid mass detail in the following specification, as shown of uniform consistency. in the accompanying drawings, and as pointed Heretofore and prior to this invention, the mixout in the appended claims. In the said drawing of paints and like compounds containing ings, which are illustrative of a preferred consolids dispersal or dissolved in suitable liquid struction of the present apparatus: 15 vehicles was obtained by the use of agitators Figure 1 is a vertical sectional view of the which operated on the order of paddles to stir apparatus constructed in accordance with and or whip the compound into shape. Not only did embodying the principles of the present inven such apparatus require excessive power and contion;

same a great deal of time, particularly in the Figure 2 is a horizontal sectional view taken 20 case of heavy-bodied compounds, but also it was on the line 2--2 of Figure 1; I rarely possible to attain in the mass the desired Figure 3 is a view partially in vertical section degree of dispersion efliciency. I taken on the line 3-3 of Figure 2;

The apparatus of the present invention in- Figure 4 is a perspective view of one of the cludes a dual set of stirring devices respectively stirrer devices of the apparatus; and 25 operating at different speeds and in diiferent Figures 5 and 6 are sectional views taken rezones within a tank of such design that every spectively on the lines 5--5 and 6-8 of Figure 4. particle of the mass being worked is directly acted Referring now more particularly to the drawupon to insure a rapid and uniform dispersion ings, it will be observed that the apparatus of thereof. The tank employed in the apparatus the present invention includes a tank llladapted 30 of the present invention contributes very mateto receive the material to be mixed. This tank rially to the high operating emciency obtained I0 is of generally polygonal shape in horizontal because its designis such as to provide in the cross-section with the corners thereof rounded, wall thereof spaced zones in each of which the as at H (see Figure 2). As. shown in Figure 2,

pressure of the mass induced by the rotative the tank is provided with four fiat sides joined 35 force of the outer stirrer arm is suddenly retogether by rounded corners and while this is leased with a consequent turbulous efiect upon the preferred construction, it will be understood the mass of material in the vicinity of the zone that the tank may be constructed of three, five of released pressure. The turbulency so induced or more sides to obtain a dispersion efficiency definitely and materially increases the speed of comparable to that of the tank shown in the v4,0 dispersion of the solid particles not only in the drawings. The bottom i2 of the tank is tapered mass located in the zones of reduced pressure and may be provided with a central opening i3 but also in the main body of the mass. Morenormally closed by a plug (not'shown) for disover, because this central body of the mass is charge and clean-out purposes. The top of the maintained in constant motion by a second set tank may be closed or not as desired. In the 45 of stirring bars no part of the mass remains construction shown in the drawings, the tank wholly or partially static as the result of which is provided with a top closure ll having a filling the undissolved particles of the mixture are preopening l5. vented from settling or massing at any onepoint. This top closure member I is provided with From the foregoing, it will be understood that a central opening i6 through which is adapted 50 it is an object of the present invention to provide to be projected interiorly of the tank the stirring an apparatus in which a dual set of stirrer dedevices or agitators to be presently described. vices operate in a mixing tank to place in posi- Mounted upon the top closure member I of tive motion every particle of the mass and to the tank and secured thereto by the bolts i1 is induce-a turbulency therein which increases the a gear box or housing ll having an upwardly a projecting vertical extension l9 through which is projected the shaft 20 of a motor 2|. This shaft 20 is suitably journalied, as at 22 and 23, within the vertical sleeve IQ of the housing l8 for free rotation about the central vertical axis of the tank "I. While in the construction shown the motor 2| is employed to directly drive the shaft 20, it will be understood that the said shaft 20 may be provided at its upward extremity with a pulley or thelike to adapt it to be belt-driven or gear-driven by any suitable power mechanism stationed more or less remotely from the mixing apparatus per se. I

The housing I8 is preferably constructed with a lower section 24 and an upper section-25 secured together by the bolts 28. the purpose of which is to render more readily accessible the interior of the housing. Keyed to the lower extremity of the vertical driving shaft 20 for rotation therewith is that one of the stirring devices shown more particularly in perspective in Figure 4 and designated generally by the reference numeral 21. As appears most clearly in said Fig-' ure 4, this stirring device 21 comprises a substantially horizontally disposed head bar 28 of Z shape, the upper branch 29 of which is keyed to the shaft 20 while the lower branch 30 thereof, which is disposed in a plane immediately beneath the top of the tank l0, projects radially of the vertical axis of the tank to a point just short of the side wall thereof. Fixed in any suitable manner to the outer extremity of the head bar 28 is 9. depending stirrer blade 3| having an inclined lower extension 32 disposed in substantial parallel relation to the inclined plane of the tank bottom. The stirrer blade 3| and its inclined extension 32 are of the obtuse angular cross-sections respectively shown in Figures 5 and 6. It will be apparent that as the head bar 28 is rotated by the driving shaft 20 about the axis of the latter as a center, the stirrer blade 3|--32 will describe a circle, the diameter of which is slightly less than the width of the tank l8 measured between opposite fiat sides thereof. The stirrer blade 3|32 thus operates to sweep through an outer portion of the massof material contained in the tank ill, the direction of rotation being such that the edges 3334 of the stirrer blade constitute the leading edges thereof and tend to cut out of the mass of material undergoing treatment a cylinder of a diameter substantially equal to that of the circle described by the vertical section 3| of the stirrer blade. The inclined lower section 32 of the stirrer blade assists in the cutting out of this cylinder from the mass in that it acts to separate said body from the bottom wall of the tank and so permit it to be freely rotated about the tank central axis.

Rotatably fitted within the horizontal head bar 28 of the stirrer device 21 to one side of the latters axis of rotation is a stub shaft 35 to the upper end of which are keyed a pair of coaxial gears 38 and 31, the stub shaft 35 therefor being journalled within a vertical socket 38 formed adjacent the inner extremity of the said head bar 28. Coaxial gears 36 and 31 being keyed to the same shaft 35 rotate in unison, the lower and larger gear 36 being in constant mesh with a large internal gear 39 fixedly secured in position within the upper member 25 of the housing l8.

. The head bar 28 of the stirrer device 21 is provided at its inner extremity with a laterally extending projection 40 having a vertical bore 4| therein through which is projected the spindle 42 of a secondary stirrer or agitator, designated generally by the reference numeral 43. The spindle 42 of this stirrer device has keyed to its upper end a gear 44 which meshes with the upper and smaller gear or pinion 31 so that upon rotation of the latter gear or pinion the secondary agitator 43 is rotated about the vertical axis of its spindle 42. As most clearly appears in Figure l, it will be observed that this secondary agitator 43 comprises a pair of parallel vertical bars 45-48 arranged in laterally spaced relation and extending downwardly to a point just short of the bottom of the tank It. It will also be noted that the axis of rotation of the secondary agitator 43 is ofiset from the axis of rotation of the 'main stirrer device 21, which latter axis is, of course,

coincident with the central axis of the tank 18.

With the apparatus arranged asjust described and particularly with the several gears entrained as shown in the drawings, it will be apparent that upon rotation of the main driving shaft 28, the stirrer device 21 (see Figure 4) will be rotated about the central vertical axis of the tank at a speed equal to that of the driving shaft 20 which ordinarily approximates 35 R. P. M; Inasmuch as the secondary stirrer 43 is carried by the, head bar 23 of the main stirrerdevice 3| but in offset relation to the axis of rotation of the latter, it follows that the said secondary stirring device is caused to describe a circle concentric with but much smaller in diameter than the circle described by the blade 3| of the main stirrer device. 1

Also, as the upper branch 23 of the head bar 23 rotates within the housing l3 about its axis of rotation, the gear 35 thereof which is constantly in mesh with the internal gear 38 is caused to rotate and imparts a like rotation to the gear or pinion 36 which is in mesh with the gear 44 of the secondary stirrer device 43. The result is that as this secondary stirring device 43 revolves about the central axis of the tank at a speed of approximately 35 R. P. M., it is rotated about the axis of its supporting spindle 42 at a speed of approximately 144 R. P. M., this latter speed being, of course, dependent upon the ratio of the entrained gears 38 and 44. The secondary stirring device 43 is thus caused to rotate or spin about a vertical axis which is itself caused to traverse an orbit having as its center the vertical axis of the tank In. The members 4546 of the second stirring device may be of any desired cross-section although preferably they are of angular or square cross-section.

In the use of the apparatus as just described, the tank I0 is, of course, filled to the desired level with the material to be mixed, this material being designated in Figure 1 by the reference character A. As the blade 3|-32 of the main stirrer device describes its circle of revolution through the mass of material A, it tends to cut out of the mass a cylindrical body for rotation within the tank A. As the vertical section 3| of the stirrer blade passes along the flat sides of the tank, the resistance of the material to the free passage of said blade is of a high order due primarily to the friction engendered in the mass by the closely adjacent side wall of the tank. However, as the vertical section 3| of the stirrer device approaches a corner of the tank, the distance between it and the wall materially intiers of the tank has the effect of creating surges in each of these zones with a resulting turbulence in the mass which is of material assistance in the distribution or dissolution of the solid particles in the liquid content of the mass. These periodic releases in the resistance of the material to the passage of the blade 3| therethrough occur regularly and as many times per revolution of the blade as there are corners to the tank, in the form of tank shown four such periodic releases being encountered for each revolution of the blade 3|. These frequent surges so induced in the mass being worked very materially increase the dispersion efliciency of the apparatus. The action of the outer vertical sweep member 3| upon the material in the rounded corners of the tank also may be described as creating a compressed volume of material which is carried or swept before the member 3| against the frictional resistance of the side walls of the tank. When this compressed volume of material is swept into the rounded corners of the tank it is met with the resistance of the relatively static material in the comer zones of the tank with the result that this latter material, in order to escape the pressure thus exerted on it, surges upwardly to create the turbulent effect above described. The extraordinary surging action thus developed in each corner zone of the tank as the verticalwsweep member 3| passes therethrough may be controlled, as desired, by suitably regulating the rotative speed of the member 3|.

Also having an important effect upon the dispersion efficiency of the apparatus is the secondary stirring mechanism 43 due to the fact that as it spins about its vertical axis of rotation it traverses an orbit of a diameter sufficiently large to insure against any static condition in the center of the mass, it being noted in this connection that the rotative speed of the sec-' ondary stirring bars 45-46 is several times greater than that of the main outer stirrer blade 3|. In other words, due to the action of this secondary stirring device the central body of the mass is constantly in agitation to such extent as to eliminate entirely the idling and down-draft center which is normally present in the paddle types of mixing devices heretofore in use. Such an idling and down-draft center is usually evidenced by a perceptible meniscus formed in the top surface'of the material being mixed. However, no such perceptible meniscus is to be observed while the material is being mixed in the present apparatus, thereby indicating that the central as well as themarginal portions of the mass are in'motion and that all particles thereof are influenced to insure a rapid and uniform dispersion thereof throughout the liquid content of the mass. 1

In order to prevent the gear shaft lubricant from entering the tank and so contaminate the material being mixed therein, it is desirable to provide an oil drip pan 48 as shown in Figure 1. This pan is aflixed to and carried by the head bar 28 of the main stirrer device and rotates therewith, the pan being provided with a marginal flange 49 to prevent the overflow of any entrained oil or grease.

As has been heretofore indicated, the top of the tank need not be closed as shown in the drawings but instead may be open and in such event the stirring mechanism may be mounted in any suitable manner centrally of the tank and at the requisite elevation, as, by means of a spider or other such skeleton frame supported from the top edges of the tank walls.

It will be understood, of course, that the invention is susceptible of various changes from time to time without departing-from the real spirit or general principles thereof and it is accordingly intended to claim the invention broadly,

as well as specifically, as indicated by the appended claims.

What is claimed as new and useful is:

1. In a mixing apparatus, in combination, a tank for receiving the material to be mixed, said tank having flat side walls joined together by rounded corners and having also a tapered bottom of substantially inverted conical shape, and an agitator disposed for rotation within said tank, said agitator including a vertically extending member adapted to describe a circle of revolution disposed in closely spaced relation with respect to the interior of the tank and includin of said flanges act to cut through the mass of also an inclined bottom member movable in a plane-spaced above and in parallel relation to the bottom wall of the tank, said agitator coacting with said rounded corners of the tank to create a turbulent condition in the material due to the suddenly reduced resistance encountered by the agitator in passing through the material in the immediate vicinity of said rounded corners.

2. In a mixing apparatus, in combination, a tank for'receiving the material to be mixed, said tank having flat side walls 'joined together by rounded corners and having also a tapered bottom of substantially inverted conical shape, and an agitator disposed for rotation within said tank, said agitator including a vertically extending member adapted to describe a circle of revolution disposed in closely spaced relation with respect to the interior of the tank and including also an inclined bottom member movable in a plane spaced above and in parallel relation to the bottom wall of the tank, said agitator coacting with said rounded corners of the tank to create a turbulent condition in the "material due to the suddenly reduced resistance encountered by the agitator in passing through". the material in the immediate vicinity of said rounded corners, said vertically and transversely extending members of the agitator being of angular crosssection and arranged so that corresponding flanges thereof project in the direction of rotation of the agitator whereby the leading edges material in the tank.

CHARLES E. FARRING'ION. 

